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Changes deferred to Revision B

Revision A remains as built. Revision B carries these changes:

  • Replace the ETA6002 and SY6280 power path with the BQ24073-based Revision B architecture.
  • Move the keyboard connector to a replaceable passive adapter.
  • Correct the TrackPoint reset circuit and profile LED order in hardware.
  • Add test access for power rails, SWD, matrix lines, TrackPoint, and backlight.
  • Keep USB/UF2 updates as the normal development path.
  • Validate backlight startup and current before enabling it in release firmware.
  • Replace the Q8/Q9 backlight switch with the controlled-rise Revision B load switch, and add the removable 5 V source link, current shunt, current-rated injection pads, and labeled power/PWM measurement points.
  • Default to USB500 for legacy and default-current sources, but fit the Revision B Type-C CC-current detector so a valid 1.5 A or 3 A advertisement can select the BQ24073's approximately 1.34 A input limit. Permit batteryless backlight operation only in those detected high-current states; otherwise require a valid battery to supplement the cable input.
  • Add a battery-voltage divider and ADC input if battery reporting remains a product requirement.

The bring-up record gives the evidence behind these changes. The Revision A schematic and purchased BOM remain the record of the manufactured board.